The orbit of a planet around a star is:

Which quantity remains constant in the orbital motion of the Earth around the Sun?

Describe the model and theory of planetary motions presented in the earliest of times.

Earth's orbit is an ellipse with eccentricity $e = 0.0167$. Thus,the Earth's distance from the Sun and its speed as it moves around the Sun vary from day to day. This means that the length of the solar day is not constant throughout the year. Assume that the Earth's spin axis is normal to its orbital plane and find the length of the shortest and the longest day. $A$ day should be taken from noon to noon. Does this explain the variation in the length of the day during the year?

If the angular momentum of a planet of mass $m$,moving around the Sun in a circular orbit is $L$,about the center of the Sun,its areal velocity is

The distance of a planet from the sun is $5$ times the distance between the earth and the sun. The time period of the planet is